For the last seven or eight years my best friend has been Matt, we went to the same school and still hang out all the time. When we were about 13 or 14, we spent the night at each other's house a lot during the summer, and this is what happened one of those nights at Matt's house.
We were in his basement watching tv and playing computer games, and he said he wanted to show me something. He led me to the other end of the basement, which was walled off, since it was his older sister Katie's room. She was at school in another state and I guess taking some summer classes, since she hadn't been around all summer. So Matt opens the door to her room and we both walk in, and he tells me he found something I might think was cool. Matt walked over to her dresser and opened the top drawer, it was full of Katie's underwear. I had never thought about girls underwear in a sexy way, but somehow knowing these were Katie's got me going. As we looked through the different pairs, I could feel my dick getting hard, but then Matt pulled a fast one on me and dared me to try one on.
Matt and I had seen each other naked tons of times when we were changing and such, and even shown each other our boners on a few occasions. But this seemed like it was too far, so I did what I thought was the best way to get out it 'I will if you will' Matt stood there for a second and asked if I was sure, and I said 'yep'. He then took off his shirt, and motioned for me to do the same, I just tried to think of it as us getting changed until we both pulled down our underwear, our dicks bouncing around. We promised to never tell people about this, and each grabbed a pair from the drawer. As I pulled on the pink cotton bikini, I almost exploded. I looked at Matt in a light blue pair of boy shorts and he looked at me, and almost instinctively we turned around for each other. I had never had such a boner in my life, and I said something about it, with Matt replying that we should do something about it.
We sat on his sister's bed in the panties and both took out our boners, looking at Matt and knowing I was wearing girls underwear I lasted less than a minute before I was cumming all over myself and the panties. Matt just stared for a second and without thinking I tapped the head of his dick and said 'come on', that was it, he just blew, all over, my hand his stomach the underwear. It was the most erotic moment of my life, and I was dressed like a girl...